ext/date: MINIT reads a stale external tz database after an in-process module restart #24350

Description

PHP_MINIT_FUNCTION(date) calls REGISTER_INI_ENTRIES() before it resets php_date_global_timezone_db:

PHP_MINIT_FUNCTION(date)
{
	REGISTER_INI_ENTRIES();          /* fires OnUpdate_date_timezone("UTC") */
	...
	php_date_global_timezone_db = NULL;
	php_date_global_timezone_db_enabled = 0;

OnUpdate_date_timezone validates the value through DATE_TIMEZONEDB, which still holds whatever the previous
startup left there. When a SAPI shuts the engine down and starts it again in the same process, and a shared extension
had installed its own database with php_date_set_tzdb() (PECL timezonedb), that pointer refers to a .so that
module_destructor() has already unloaded. The second startup then reads unmapped memory: a segfault, or a hang
where the SAPI's signal handling swallows it.

Neither the extension nor date's MSHUTDOWN clears the pointer, and the extension can't safely do it itself:
php_date_set_tzdb(NULL) dereferences its argument.

Who hits it

Any SAPI that restarts the engine in-process with timezonedb loaded:

• Apache mod_php on a graceful reload: 2025.2 segfault on Apache mod_php reload pecl-datetime-timezonedb#16 has the backtrace
  (seek_to_tz_position ← timelib_timezone_id_is_valid ← OnUpdate_date_timezone ← zm_startup_date).
• FrankenPHP ≥ 1.12.5, which restarts the engine on a watched-file change, an OPcache restart or opcache_reset():
  Segmentation fault on FrankenPHP reload after installing timezonedb with PIE ZTS frankenphp#2667.

Reproduction (FrankenPHP 1.13.0, PHP 8.5.11 ZTS, Docker)

A minimal worker script with watch on one file; touch that file, then send one request. With only timezonedb
loaded, the restart never completed in 9 of 10 fresh containers. Without it, 0 of 10. With
ZEND_DONT_UNLOAD_MODULES=1, which keeps the .so mapped, 0 of 20.

Suggested fix

Reset the pointer before the INI entries are registered (or in MSHUTDOWN):

PHP_MINIT_FUNCTION(date)
{
	php_date_global_timezone_db = NULL;
	php_date_global_timezone_db_enabled = 0;

	REGISTER_INI_ENTRIES();
	...

PHP Version

PHP 8.5.11 (same code on master)

Operating System

Debian (dunglas/frankenphp:1.13-php8.5), aarch64